Parque da Juventude. Sao Paulo.
Once the site of a notorious jail, this is another example of existing structures being converted into a public space. This park has many steel and concrete structures forming the vertical elements of the spaces. The combination of concrete piles and trees is especially effective.
'Up' is expensive. It's better to work with what you have. Introducing any vertical element whether it is tree or structure will cost you, or your client. Better to convert what is already there. Plus as the picture shows, you can create some really interesting, moody spaces.
Not a great deal of information out there on the park, unless you speak Portuguese. Click through to a Flickr page with some good shots of the park.